Plastic waterproof coating for blasting dynamite and the like



July 11, 1933. p, E,.PEAR$ALL 1,917,540

PLASTIC WATERPROOF COATING FOR BLASTING DYNAMITE AND THE LIKE Filed Aug.5, 1931 Patented July 11, 19 33 UNITE STATES PATENT oFFicE DAVID E.PEARSALL, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO THE ENSIGN- BICKFORDCO., OF SIMSBURY, CONNECTICUT, A CORPORATION OF OONNECTIOUT PLASTICWATERPROOF COATING FOB. BLASTING DYNAMITE AND THE LIKE Application filedAugust 5, 1931. Serial No. 555,234.

ly of cylindrical shape. varying from about eight inches to twenty-fourinches in length and of various diameters from about one inch upward,the explosive charge being wrapped in paper, the ends-of which arefolded in and the resulting cartridge coated with parafline.

'Notwihstanding the fact that the cartridges ofthis type have been inalmost universal use for a long period of years, they possess inherentdisadvantages, among which may be enumerated the following: Theparaffine is usually of low melting point so that in hot weather itmelts, causing the cartridges to stick together in the packing box. Themelting of the paraffine also allows the nitroglycerine to exude throughthe paper, thus giving rise to a source of danger. When used in mines,the paper on the cartridges is usually slit and at times it becomesnecessary to entirely remove it so that the charge may be spread insidethe drill hole. It is also necessary to take into account the chemicalcomposition of the paper casings of the cartridges in order to secure aproper oxygen balance of the explosive charger;- w

I have found that the foregoing disadvantages enumerated, and othersnotspecifically set forth, can be obviated 'by the simple expedient ofomitting the paper wrapper entirely and directly coating the dynamite,gclatine or other explosive with a plastic waterproof material, which ispreferably of suflicient'strength and rigidity when set, to hold thecartridge in its original shape.

The coating materials which I have found practicable for this purposeare waxes, lacquers, rosins, rubber, asphalts, tars, and practicallymost other materials embodied in the broad class known as plastics. Morespecifically, the petrolatum stock waxes which have ceresine-likeproperties have been found par-- ticularly adaptable for this purposesince they have a relatively high melting point, are im-' inside thedrill hole.

pervious to nitroglycerlne, and are frangible when suflicient pressureis applied thereto. so that the explosive charge may be easily spread Ihave also found that excellent results are obtainable with the celluloseacetate and cellulose nitrate lacquers. The explosive cartridge orcharge may be coated by dipping, spraying, brushing or otherwiseapplying the plastic waterproof composition either in the melted stateor in solution to a self-sustaining mass of dynamite gelatine or otherexplosive body and permitting said coating composition to set in in situthereon. The explosive cartridge as thus formed has a so-called skincoating of waterproof composition which is of substantially uniformthickness throughout and which is coextensive with the explosive mass.

An explosive cartridge embodying the pres ent invention is illustratedin the accompanying drawing, wherein a self-sustaining, cylindrical massor stick of explosive, such as dynamite A, is entirely enclosed withinaskin coating B of a plastic waterproof material which is formed in situon the mass A. The coating B is of suflicient rigidity when set tosustain the explosive charge A in its original shape.

From the foregoing detailed description it will be appreciated that theproduction of explosive cartridges or charges of the char.-

acter described will not only speed up the tion of substantially uniformthickness throughout, which is co-extensive with the explosive.

2. A blasting cartridge comprisin a charge of explosive ofself-sustaining orm having a coating of a cellulose plastic ap-' plieddirectly thereto and entirely enclosing said cartridge.

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4. An article of manufacture consisting of a blasting cartridge orcharge of the type embracing dynamite and blasting jellies having a Waxcomposition coating applied directly thereto and coextensive therewith,said wax composition having a relatively high melting point.

In witnesswhereof, I have hereunto signed my name! DAVID E. PEARSALL.

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